Photorecording



Sept. 27, 1949. F. URBACH 2,482,814

PHOTORECORDING Filed March 26, 1946 V 10: 3/, FIG.1.

J] l7 PHOsPHOR kil "V- ar (C 16 l 15 Z4 21 22 I I; 10

FIG.5.

. FRANZ URBACH INVENTOR BY mfm ATTY & AG'T Patented Sept. 27, 1949 PHOTORECORDING Franz Urbach, Rochester, N. Y., assignor to Eastman KodakCompany, Rochester, N. Y., a corporation of New Jersey Application March 26, 194.6, Serial No. 657,136

This invention relates to photorecording and has for its main object the provision of a method of delayed action photorecording.

The term photorecording is here used to refer to the recording of light, usually photographic, but in some cases the final step may be actually a manual one. The process here described should be compared to that described in my application Serial Number 657,135 filed concurrently herewith, the two processes having different advanl tages for different purposes. Reference is also made to my concurrently filed application Serial No. 657,137 having to do with a third system of photography, particularly for infrared photography, by using in part phosphors of the same type as used in the present invention. The infrared photography case is limited in its utility to relatively long wavelength infrared light because at shorter wavelengths, photographic emulsions can be directly sensitized. However, the present invention has advantages which make it useful in the visible as well as in the infrared regions.

For certain purposes the present invention is the most useful of the three. It is particularly useful for photocopying and, because of the high gamma (approaching 2) inherent in the process, it is useful for reflex copying.

According to the invention, a phosphor of the type to be described below is uniformly excited with short wavelength radiation and then an image is formed on the phosphor, either by contact or projection printing using light of nonexciting wavelength in order to exhaust the excitation of the phosphor layer in proportion (not necessarily linear proportion) to the image intensity. This exhausting may be entirely due to the stimulating of the phosphorescence or it may be due to stimulation combined with the quenching effect which occurs with some phosphors (or even to quenching alone by non-stimulating wavelengths but this is quite rare). In either case the phosphor is exhausted where illuminated by the image and now contains in amounts of excitation, a negative image relative to that which was exposed. It will be noted that the phosphor layer could be stored either after the excitation or following the image exhaustion, if any reason for storing occurs. In any case the next essential step of the invention is to place the excited phosphor layer containing the latent exhaustion image in printing relation (contact or projection printing) to a layer of material on which a permanent record can be made. In gen- 6 Claims. (Cl. 250-65) eral this is a photographic layer, but hand tracing of simple images may be useful in some cases.

With the recording layer in place, the phosphor layer is then uniformly illuminated with stimulating light, preferably red or infrared light to produce on the recording layer by stimulation, an optica1 image in the wavelength which the phosphor emits. The illumination may be over one area of the phosphor layer at a time. The wavelength emitted is longer than that of the exciting radiation and when red or infrared is used as the stimulating radiation, the wavelength emitted is shorter than the stimulating radiation. The luminous image formed on the recording layer is negative to the image which exhausts the phosphor layer. In the case where the recording layer is a photographic one, normal processing will produce an image positive with respect to the exhausting image.

When the exhausting is carried far enough to reduce the excitation (stimulable brightness) of the least exhausted areas to /3 of the unexposed value, the later stimulated image will have a relatively high gamma approximating 2. It will be noted that the exhausting exposures are of reasonably short time when using the highly sensitive phosphors described below.

The following examples are given of the composition of infrared sensitive phosphors which are particularly useful in the present invention. There are others which will work, but perhaps not as well as those here listed. As pointed out in my copending applications relative to the preparation and composition of phosphors themselves, each phosphor mustinclude a base, a flux and at least one activator. The flux is used in the usual way in small percentages to bond the materials during firing. The concentrations of the activators appear in parts per million by Weight relative to the whole phosphor after firing. The exact value depends on the specific details of the preparation and the quantities may be varied from those given without materially affecting their use for the present invention. The preparation of these phosphors follows the conventional methods used in preparing ordinary phosphors, it being noted that the sensitivity can be Varied depending on the degree of oxidation of the sulfides or selenides.

This list is not as long as in my other case, only the ones most useful for the present invention being here included, but of course any of them could be used. The phosphors most easily exhausted are preferable in the present case.

Activators Eu 100 Sm 100 Go 100 S111 40 Cu 100 Sin 20 Ce 100 S11 10,000 Cu 100 Bi 100 Pb 100 M11 200'Ou l Pb 40,000 On 1 Pb 40,000 Cu 20 Eu 100 Sm 100 Eu 100 Bi 100 In my copending application Serial; Number 657,137, item No. 6 was recommended'for use at Dry Ice temperatures, but for the present invention, it is quite useful at room temperature since it is easily exhausted.

Some of these particular phosphors were developed by me as is indicated by my oopending applications referred to.above.

The manner in which the present inventiorrmay be performed will be fully understood from the following. description when. read in connection with the accompanying drawings in which:

Figs- 1, 2, and 3 constitute a .flow chart illustrating one embodiment of. the invention.

Fig. 4 similarly illustrates another embodiment of the invention.

' Fig. 5 shows anarrangement. alternative to one of the steps illustrated in Fig.4.

. In Fig. 1 light from an .ultraviolet lamp. l l uni- .formly excites a phosphor I0, which eitherimmediately. or after. suificient relaxationtime to ,allow the. spontaneous afterglow. to 'die down, is moved as indicated by the arrow I 2 into printing relation with anobject. It, a pictureof which. is desired. The object is illuminated. by yellow, red

.and infra red light by lamps: I1 and lightfrom the object is brought .tofocus by a lens. 15 on the phosphor ID as shown in Fig.2. This is allowed to continue long enough to. exhaust the excitation inthe phosphor Impreferably bystimulation alone since the best phosphors are those which have a high stimulation efiect, butthe exhaustion may be at least partly by a quenching efiect. The layer A I containing the, latent negative image in degrees of exhaustion may bestored or maybe moved directly as indicated by the arrow 20 into printing relation v.with. a permanent, recording layer 23. The layer Ill, is then uniformlyJilh1minated with infra red light from lamps 2i and the negativeimage'. therein is photographed'by lens 22 of a camera 24 onto the photographic film 23. .The film23 is thendeveloped directly to an image positive with respect to .the object l5.of Fig.2. As in my copending applicationserial No; 657,135 referred to above this permanent recording. may,

in the-case of simple line images, betraced 60 illustrated here.

A particularly useful embodiment offthe :in-.

vention is illustrated-'in'Figa l. 'In this case: ultraviolet or short wavelength visible-light: from lamp 30 uniformly excites :a, phosphors; 3 hwhich -is-moved to the position-32-inicontact= with a positive record 33 which may-bea printed page or the like. The printed page is then .floodlighted with infra red from a lamp: 34..which stimulates and thus exhausts the excitationin the phosphor 3.2.

The phosphor 32 containing thelatent exhaustion image is then placed in contact with a photographic layer 40 and printed by flooding with infra red light from a lamp 35. The flooding illumination may be either from below as shown or through the photographic layer 40 as from lamp 42 shown in broken lines. Successive prints may be made as shown by moving the phosphor layer intovcontact withanotherphotographic .layer 4|. Preferablytheintensity ofthe lamp 35 is increased for successive printings in order to keep the brightness of the phosphorescent image at a high level. I have found that a "plurality of prints may be made from a single phosphorescentimage in this manner.

.-Because of the high gamma obtained with this method it is" quite possible to make the exposure to the original image 33 by reflex printing as illustrated in'Fig. 5. That is, infra red light ,rfrom lthe lamp 45 passes through the phosphor layer 32 and is reflected from the printed page 33. The phosphor is uniformly exhausted .by the slight. directly from the lamp 45 but modifierentially exhausted by the light reflected from-.the

printed-page. The-over -all flooding tends to reduce the contrast, of course, but..the..pr0cess has adequate contrast to allow for this.

Having thus described thepreferred: embodimerits my invention I Wishto point outthat it is not limited to these structures but-.ds'of. the scope ofthe appended claims.

I claim:

1. The method of delayedactionphotorecording of a long wavelength image which comprises (a) substantially uniformly. exoitingwithshort wavelength radiation .a layenotaphosphor of .the type-whichstores the excitation energyand "releases at least partof it,.in.trigger fashion-when stimulated by. longer -wavelength .light, the released energy being light of.-wavelength. intermediate-between: the excitingaand stimulating =radiationwavelength, (b) forming an imagedn saidi-longer wavelength lighton the-phosphor layer to exhaust the excitation of the phosphor 2 layer in proportion to the imageintensity atileast :partly .by stimulating then (0) --placing the. exciteds-phosphor layer containing the latent exhaustion' image therein in printing relationto a layer of material on-whicha x-permanent record canbemade; -(d) illuminating the phosphor layer with said-longer wavelength light to produce on therecordinglayer by stimulation an optical image insaid intermediate wavelength light.negative to said 'longerwavelength imageand (e) pro- H ducing a permanent record ,inaccordance with the negative image on the recording layer.

2. .Themethod according. to claim 1- in which \the-perrnanent recording material is a photo- 5 graphic material and the record -is produced therein by-direct processing to a-positive relative .to.-said. longer wavelength image.

:3. The method according to claim 1 in-which the'image forming is done lay-placing a picture i to be recorded in-contact with the phosphor layer :-and--exposing the layer through the-picture by said longer. wavelength light.

4. The method according to claim 1 in-Whi'ch the image forming is done by placing-a picture to be recorded in contact with the phosphor layer and then refiexexposing the layer by said longer wavelength light through the layer to thepicture and reflected therefrom, the exhausting oi the .excitation being carried to the point where the .-least exhausted area has=dropped to less than-one third of its-original excitation. value-whereby the later stimulated image will have a relatively high gamma.

5. The method of delayed action photorecording of a radiant image which comprises (a) substantially uniformly exciting with radiation of a 5 given wavelength a layer of a phosphor of the type which stores the excitation energy and releases at least part of it, in trigger fashion, when stimulated by a different wavelength light, the released energy being light of wavelength longer than said given wavelength (b) forming an image in a wavelength different from said given wavelength on the phosphor layer to exhaust the excitation therein in proportion to the image intensity, then (c) placing the excited phosphor layer containing the latent exhaustion image therein in printing relation to a layer of photosensitive material, (d) illuminating the phosphor layer uniformly with light of stimulating wavelength to produce an optical image which exposes the photosensitive layer and (6) processing the photosensitive layer to a record positive relative to said difierent wavelength image.

6. The method of delayed action formation of a visible image from a long wave length image which comprises substantially uniformly exciting with short wave length radiation, a layer of a 6 phosphor of the type which stores the excitation energy and releases at least part of it, in trigger fashion, when stimulated by longer wave length light, the released energy being visible light of wave length intermediate between the exciting and stimulating radiation wave length, forming an image in said longer wave length light on the phosphor layer to exhaust the excitation thereof in proportion to the image intensity and then later illuminating the phosphor layer with said longer wave length light to produce by stimulation an optical image in said visible intermediate wave length light negative to said longer wave length image.

FRANZ URBACH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,565,256 Christensen Dec. 15, 1925 1,648,058 Parker Nov. 8, 1927 1,724,572 Geisen Aug. 13, 1929 1,996,492 Schroter Apr. 2, 1935 2,074,226 Kunz et al Mar. 16, 1937 

